The present invention relates to an apparatus and a composition for carrying out a self-sealing treatment to impart self-sealing properties to pneumatic tires, and further relates to the tires so obtained. More particularly, the invention relates to an apparatus by which a uniform layer of a self-sealing composition can be applied to the inside surface of the tread of tubeless tires.
Moreover, the present invention pertains to a composition that can be applied to the inside surface of the tread of tubeless tires to form a highly stable adhering layer on the inside surface. The layer is capable of sealing punctures that commonly occur in the tread.
The present invention also relates to tires treated according to the present invention. So treated the tires are sealed against air leakage despite punctures in the tread surface caused by common size nails.
The various problems caused by punctures in the tires of motorcars have been addressed up to the present time by recourse to various pre-treatment or post-treatment systems for the tire.
Without particular reference to the details of post-treatment systems, it should be noted that conventional pre-treatment techniques substantially rely on compositions containing a sealing activity component mixed with adhesive compounds, especially rubber compounds, as well as with a gelling agent such as an olefinic polymer. These compositions are intended for application to the inside surface of the tire before or during other operations on a tire to obtain pneumatic tires which will deflate to a lesser degree as a consequence of a puncture to permit riding on the punctured tire.
A well known composition (see GB Pat. No. 1,570,398) is directed to easier relative slipping between the contacting portions of the inside surface of the tire when the same becomes deflated to pressures down to the order of 1-5 psi (or 0.070-0.35 kg/cm.sup.2). The composition is characterized in that it contains as a sealing agent a particle material consisting preferably of rubber granules or "rubber crumb", or of wood dust, with limits on the sizes of the particles and their volume percentages.
However, it is to be noted that the use of sealing materials made up of asbestos fibers or of glass within conventional compositions of the type mentioned above, and suggested in the present invention, are directed to obtaining a faster sealing rate and more complete seal in order to prevent the tire from deflating as a result of punctures. Also, for the full safety of the driver, access to pressure detecting means, for instance to recently developed electronic pressure switches arranged inside the tire could be provided.